CVE-2025-62517: 
JavaScript vulnerability analysis and mitigation

Rollbar.js, a JavaScript error tracking and logging library, was found to contain a prototype pollution vulnerability (CVE-2025-62517) in its merge() function. The vulnerability affects versions before 2.26.5 and versions from 3.0.0-alpha1 to before 3.0.0-beta5. This security issue was disclosed on October 23, 2025 (GitHub Advisory).

The vulnerability is classified as CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes) with a CVSS v3.1 score of 5.9 (Medium). The vulnerability exists in the merge() function, where if application code calls rollbar.configure() with untrusted input, prototype pollution becomes possible. The CVSS vector string is CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N, indicating network accessibility with high attack complexity, no privileges required, and potential for high impact on integrity (GitHub Advisory, Miggo).

The vulnerability could allow attackers to modify the prototype of objects in the application through untrusted input passed to the rollbar.configure() function. This could potentially lead to application-wide integrity issues through prototype pollution (GitHub Advisory).

The vulnerability has been fixed in versions 2.26.5 and 3.0.0-beta5. As a workaround, users should ensure that values passed to rollbar.configure() do not contain untrusted input. The fixes involve preventing modification of Object.prototype by creating objects without prototypes using Object.create(null) (GitHub Advisory).